Determination of air-gap eccentricity in electric motors using coherence analysis

This study addresses the detection of air-gap eccentricity based on bearing damage in 5 hp induction machines. The faulty condition of the bearing is caused by accelerated aging processes in seven aging cycles. For the faulty case, the spectra of vibration signals are computed for initial and final aging processes under 100% load condition. Subsequently, the spectra of the current signals for a single phase are also obtained for the initial and aged cases and cross-power spectral coherences between the vibration and current signals are computed.